Usage of security films is increasing with importance of information protection or personal privacies. For example, Patent Document 1 (Korean Patent Laid-Open Publication No. 2007-0090662) discloses a security film applying the micro louver technology. A micro louver film has a structure in which a number of micro-louvers are patterned at regular intervals. A number of micro-louvers formed inside the louver film exert an effect (direction control effect) of controlling the traveling direction of light penetrating the louver film to a predetermined exit angle range. Therefore, it is possible to prevent unnecessary exit of light penetrating the liquid crystal panel to the lateral direction, and such a louver film is also referred to as a light control film. However, in the micro louver film, an aspect ratio is a major factor of the security film performance, where the larger the line width is, the lower the height may be, but there is a problem that if the line width increases, the transmittance decreases.